Piezo motors of this type are known from the following documents: DE 10 2006 004 194; EP 0 951 078; WO 01/41228; and EP 1 192 704.
In these piezo motors, electrical oscillations are converted into mechanical oscillations by means of the reciprocal piezo effect, and these mechanical oscillations of a drive finger are used to drive a rotor. Even if the deflections of the drive finger are very small, a sufficiently high rotational speed of the rotor is achieved owing to the high speed of these deflections.
In the known piezo motors, the drive finger is formed by a resonance body which is made to oscillate by an oscillation generator made of a piezo-electric material. The oscillating end of the drive finger is pressed against an annular face of a rotor by a spring device, and as a result a frictional contact is brought about.
The frictional contact of the drive finger with the rotor has the disadvantage that the oscillating contact face of the drive finger wears relatively quickly and the component which runs in the drive direction is not fully utilized. In addition, only very small forces can be transmitted from the drive finger to the rotor.
Accordingly, it would be desirable to provide a piezo motor in which the transmission of force from the drive finger to the rotor is improved.